Molecular beam epitaxy growth of wurtzite AlN nanotips

The characteristics of structure and morphology of AlN nanotips grown under higher V/III ratio on Si (111) with plasma-assisted molecular beam epitaxy are herein investigated. We found that the AlN nanotips were single crystalline with {1-211} inclined facets and embedded in pitlike defects of N-polarity. The density and size of the AlN nanotips can be controlled by the growth conditions. The AlN nanotip growth mechanism can be rationalized as the c-type dislocations generated between two adjacent grains due to the formation of higher strain area in the early stages of growth. The c-type dislocation would reverse the stacking sequence of the following adatoms, leading to the AlN nanotip growth with inverse polarity and higher growth rate compared to the surrounding matrix. These nanotips might serve as the ideal templates for further growth of nanostructure devices.